Everyone, except Canonical I guess, expected Mir to cause a major mess for the global Linux community. Did Canonical care?

Did you expect them to, given past behaviors? I think everyone be they application developers, library maintainers, graphics driver gurus, etc should just make a concerted effort to stop working on anything related to Canonical. They want to do it themselves? Let's see them do just that.
Note, I'm not being spiteful here. I would actually love to see this exact result happen not to destroy Canonical, but so that we might eventually get a somewhat integrated ecosystem. On which side such integration will happen is something I cannot predict. The wider community has more resources, but very little direction. Canonical are the reverse: they obviously know what they want and why, but aren't focusing as much of their resources on it as they should and are being hampered in some ways by the community. I think Canonical should be put through the crucible, so to speak. I think they have it in them but, as long as they're concerned with the wider community's development and reactions, they won't ever focus on themselves enough to make their operating system happen.